Qi Xin, Wan Baoquan, Zhang Jun, Wang Quan, Chen Haibin, Zhao Qiancheng, Wang Binwu
China Electric Power Research Institute, Wuhan 430074, China.
State Grid Shanghai Municipal Electric Power Company, Shanghai 200050, China.
Rev Sci Instrum. 2024 Jul 1;95(7). doi: 10.1063/5.0209242.
This paper proposes an active on-site calibration method through background current cancellation and non-rated current injection. It can measure the error of the current transformer in service from 1% to 120% rated current percentage without power supply interruption. In order to establish the error relationship between rated frequency and arbitrary frequency, a theoretical analysis of current transformer calibration at the arbitrary frequency has been developed by means of the equivalent circuit. It describes a method to determine the phase angle and ratio errors of the measuring transformers at arbitrary frequencies on the basis of the calibrated error values at rated frequency. To prove the theoretical analysis, an experimental validation was carried out. The experimental results demonstrate that this active onsite calibration is a valid tool for the evaluation of current transformer performances. The calibration results showed that, for both cases (non-rated frequency calibration and mixing frequency calibration), the difference between mean ratio error and rated frequency ratio error was lower than 0.01%, and the difference between mean phase error and rated frequency phase error was lower than 1', which meets the requirement of the 0.2 accuracy class calibration.
本文提出了一种通过背景电流消除和非额定电流注入的有源现场校准方法。它可以在不中断供电的情况下，测量运行中的电流互感器在1%至120%额定电流百分比范围内的误差。为了建立额定频率与任意频率之间的误差关系，通过等效电路对任意频率下的电流互感器校准进行了理论分析。它描述了一种基于额定频率下的校准误差值来确定测量互感器在任意频率下的相角和变比误差的方法。为了验证理论分析，进行了实验验证。实验结果表明，这种有源现场校准是评估电流互感器性能的有效工具。校准结果表明，对于两种情况（非额定频率校准和混合频率校准），平均变比误差与额定频率变比误差之间的差异低于0.01%，平均相位误差与额定频率相位误差之间的差异低于1'，满足0.2精度等级校准的要求。
